M. Tanaka et al., SPACE-RESOLVED AND TIME-RESOLVED OPTICAL SPECTROSCOPY OF PLUMES GENERATED BY LASER-ABLATION OF NIO IN A VACUUM, Journal of applied physics, 83(6), 1998, pp. 3379-3385
Laser ablation of NiO at 266 nm has been studied by measuring absorpti
on spectra and emission spectra which are resolved both temporally and
spatially. The spectra were measured at several points 1 mm apart fro
m the laser spot and with several detection angles. Ablated species in
different electronic states such as the ground state, lower lying sta
tes, and excited states are distinguished from absorption and emission
spectroscopy. Time-of-flight spectra of these species and their angul
ar dependence are obtained. It is revealed that excited Ni neutrals ar
e generated mainly by the recombination of Ni+ ions with electrons, an
d Ni+ ions ejected nearly normal to the surface are exclusively excite
d due to multiple collisional effect. The isotropic angular dependence
of most probable velocities of Ni+ ions and Ni neutrals an explained
by ambipolar diffusion of the plume. The mechanism of species ejection
is also discussed. (C) 1998 American Institute of Physics.